Receiver for wireless telegraphy.



R. H. RENDAHL.

REGEIVER POE WIRELESS TELEGRAPHY.

APPLIOATION FILED NOV.1, 190G.

9%A26 Patented June 6,1911.

wow-uni: v, ac-(arm WILNELMS coup m1 RAGNAR I-IAKAN RENDAHL, 0F BERLIN, GERMANY, ASSIGNOR '10 GESELLSQHAFT FfiR DRAHTLOSE TELEGRAPHIE M. 13. I1, OF'BERLI EN, GERMANY.

Todlhwkom it may concern:

' Be it known that I, RA NARH KAN REN- DAHL,& subject of the King of Sweden, 112- ceivers for WVireless Telegraphy, of which the following is a full, clear, and exact description, reference being had to the actcompanying drawing, forming a part of this specification. This invention relates to those receivers forwireless telegraphy which work in con junction with detectors, which even in a sistance and respond to current intensities.

To such detectors there belong, among others, the electrolytic'cell, the microphone contact, the mercury vapor "lamp, the bolometer and the like. Now in such receivers it is essential to make the proportion between the energy per oscillation conveyed to the detectorand the energy of an oscilla. tion produced in the'resonance clrcuit of the receiver, easily. variable, as experiments have shown that on'the'porrect choice of this proportion, the sensitiveness of the receiver and also the sharpness'of its tuning depend.

Hitherto insuch receiversthe detector was inserted in parallel to-a variable condenser and a direct-current was conveyed to the detectorby the intermediary of chokin coils.

{the detector in an oscillation circuit.

By the electric connection therebyormed between the choking coil and the condenser a circuit was formed which on receiving electric oscillations might easily come into resonance, whereby a considerable weakening of the total intensity and under certain circumstances an interruption in the receiving, might arise. Another arrangement as heretofore used in practice isto .conneIct n this case the tuning of the receiving station to an unknown wave length represents a mutual adjustment of two'unknown factors, owing to the connection of 'twotuned circuits which are independent of each other; because the detector responds only-when both circuitsiare tuned to the unknown length of: the waves emitted from the sending station; Thus the tuning operation may be considered in this particular case as a series of experiments which usually require a great amount of time; By this invention RECEIVER FOR WIRELESS TELEGRAPH Y.

' Specification of Letters Patent. Application filed November 1,1806i Serial No. 341,565.

Patented J none 6. 1911.

the receiver attaine'dina practical, advantageous manner.

The invention consists substantially in the detector being branched off from a self-induction coil lying in a resonance'circuit of the receiver. It is essential in this that the part of the self-induction which is common to the detector and the resonance circuit should be variable and that the detector circuit is aperiodic. 'Acondenser is preferably interpolated in the detector circuit with which an indicating instrument and the source of elcctromotive force are connected in parallel." The connection of the source of electromotive force with the detector is then preferably done by the intermediary of a potentiometer in order to be able to exactly regulate the extent of the electromotive force conveyed to the detector.

In case no condenser is in the'detector circuit the condition that this circuit should be aperiodic is fulfilled without any further arrangement. If a condenser is inserted aperiodicity is obtained when the condenser is chosen sufficiently large as is the case when condensers are used, the principal purpose of which is to prevent the flowing of the direct current.

Various methods of carrying out the in-' vention are shown diagrammatically in Figures 1-4 of the accompanying drawings.

Fig. 1 shows a simple receiver in which the receiving circuit is formed of an aerial conductor 1, a variable self-induction coil 2, a self-induction coil 3. a variable condenser 4 and a conductor 5 which is connected with the earth or a counter capacity. The tuning Y I of this receiving circuit takes place by vari ation of the self-induction coil 2 and the condenser 4. From the self-induction coil 3 the detect'or circuit is branched off which con tains a detector 9 and acondenser10. In

the present case an electrolytic cell isemployed as detector. The source of electromotive .force 13 is connected in parallel to the condenser by means of a potentiometer 12. The potentiometer conductor.also contains an indicator 11 by means of which the alter- I ation of the intensity in the detector circuit may be ascertained. In tuning the receiving conductor it is preferable to first branch ofi' the detector circuit from the ends of the self-induction coil 3-and in this arrangement the tuning is elfected by altering the tuning means in the receiving conductor until the detector circuit, is gradually diminished and then the self-induction and capacity in the receiving conductor simultaneously afterward suitably regulated. A. value of the self-induction lying in the detector circuit is thus attained, at which the sensitiveness of are the greatest.

, A Fig. 2 shows a receiver in which the receiving conductor is, conducti'vcly coupled witha closed resonance circuit. The resothe self-induction coil 3 and is formed by this, the conductor '14: and the condenser 7. The detector circuit is branched ofl from the art ofthe self inductioncoil 3 which beon'gs in common to the receiving conductor and the resonance circuit. The tuning of .the receiving conductor takes place in the "manner hereinbefore described, after which the tuning of the resonance circuit by altering the condenser 7 and ing the'size of the part of the self-induction coil which part only lies in the resonance circuit, then takes place.

Figs. 3 and 4: are diagrams of the receiver connections, in which the receiving conductor acts in conjunction with the resonance circuit by means or" a transformer. The selfinduction coil 3 of the receivin conductor here forms the primary coil 0 former, the secondary coil 6 of which, lies in the secondary circuit. In the connections shown in Fig. 3 this secondary resonance circuit contains in addition to the secondary coil 6 a variable condenser 7 and a self-induction coil 8 with variable self-induction. This coil consists of two parts acting inductively on one another, which are movably arranged to one another in such a way that, by 4 altering their mutual position, the total selfinduction of the coil is altered. From this variable selfinduction-coil the detector 9 is branched oil in series .with the condenser 10. Otherwise the arrangement corresponds to that described with reference to Figs. 1 and 2.

The tuning of the receiving conductor takes place in similar manner to what was described with reference to Fig. 1, but the electriccoupling between the primary and secondary coils made initially, however,

the coil 8 as large as possible,

and the self-induction of the coil 6.

the receiver and the sharpness of the tuning 'nance circuit'is here again branched offfrom eventually by var cator in the present invention.

the transdo claim and desire as tight as possible and the self-induction of so that as much energy as possible'is'thus conveyed to the detectorfrom thereceiving conductor. 1 The sharper tuning then takes place under gradual loosening of the coupling between 3 and '6 and diminution of the self-induction of the coil 8. The tuning of the resonance circuit takes place by variation of the condenser 7 v The receiver connections shown in Fig; 4; only substantially difier from those hereinbefore described by the detector circuit not being branched oil a separate self-induction lying in the resonance circuit, but from a portion of the secondary coil. Further, this I arrangement shows means for easily enabling the detector circuit to be branched off from certain points of the primary and secondary coils. For this object the endsof the con ductors coming from the detector and the condenser 10 are provided with plugs as g. which fit into switch bushes 15 on the ends of the primary coil and switch bushes 16,17, 18, 19, of the secondary coil. 'For the pur pose of tuning the receiving conductor,*the two plugs are first switched into thebushes 1 15 on the receiving conductor and'then'the rough or crude tuning of the latter is effected. When this has been done the proportions in the transfer of energy to the' detector may be gradually alteredand brought to thedesired value, the plugy being inserted in the bush 19 and the pld a2- successively inth'e bushes 16, 17, 18, a er which the value may be further diminished by inserting the plugs m and y in the bushes -17, 18, and 16, 17, respectively.

Any suitable instrument of known such, for instance, as a galvanometer, a tele-v phone or the like may be employed as indi-,

' Having explained my inyention, what l to secure'by Letters Patent is:-

1. A receiverfor wireless telegraphy comprising anoscillating circuit containing a self induction coil, an aperiodic circuit branched ofi' from the self induction coil, a detector responding to current intensities and a condenser included in said aperiodic circuit, substantially as described.

2. A receiver for wireless teIegraphy cQmprising an oscillating circuit containing a self induction coil, an aperiodic circuit branched 120 OK from the self induction coil, a detector responding 'to current intensities and a condenser included in said aperiodic circuit, and means fbr varying the self induction of the coil connecting the oscillating circuit with the aperiodic circuit, substantially as described.-

3. A receiver for wireless telegraphy comprising an oscillatingmircuit, containing a self induction coil, an aperiodic circuit 130 branched off from the sell induction coil, a detector respbnding to current iIli'Ol'lSli'ltiS, a condenser included in said aperiodic circuit and an indicator pa allel to the said condenser, substantially as described.

4. A receiver for wireless telcgruphy comprising an oscillating circuit: containingan induct-ion coilan aperiodic circuit branched off from said induction roihn (iPllKlUI n sponding to current intensities. a condenser included in said aperiodic circuih means for \illyillg [he self-indiwliou of (he coil roumeeting the oscillating circuit with the aperiodic circuit, and an indicator parallel to the said condenser, substantially as de- 15 scribed.

In witness whereof, I hereunto subscribe I 1111) name this 10th day of September A. I). E m).

IHUCAR IIAKAN llllNDAllL.

i Witnesses: 1

1 A IJHCRT (i i-usimnenu. 

